Providing fault-tolerant authentication and authorization in wireless mobile IP networks

In wireless Mobile IP systems, the authentications and authorizations are performed by AAA (Authentication, Authorization, and Accounting) servers. An AAA server associates with a mobility agent to form an administrative domain. If an AAA server fails, all the mobile nodes (MNs) within the corresponding domain (failure-effected MNs) are unable to execute data services since their authentications and authorizations cannot be performed by the faulty AAA server. To tolerate the failure of the AAA server, this paper presents an efficient fault-tolerant approach. Once a failure is detected in an AAA server of an administrative domain, the proposed approach utilizes the AAA servers in other administrative domains to virtually generate a backup AAA server. To further reduce the fault-tolerant cost, the proposed approach additionally uses two techniques: preservation and tracking to assist the generation of the backup AAA server. Due to introducing these two techniques, the proposed approach does not need to retrieve the AAA records of failure-effected MNs while performing fault tolerance. Finally, we use M/G/c/c queuing model to analyze the effectiveness of the proposed approach over previous approaches. The analytical results are also validated by simulations.